Barrier Mask

ABSTRACT

A barrier mask, or face mask is provided that includes a mask body that includes a filter portion, an upper elastic portion, and a lower elastic portion, where the mask body includes at least one meltblown layer. The face mask also includes one or more elastic straps. A method of forming a face mask is also provided, where the method includes electrostatically treating the meltblown layer during the face mask formation process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 63/028,889, having a filing date of May 22, 2020, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Face masks find utility in a variety of medical, industrial and household applications by protecting the wearer from inhaling dust and other harmful airborne contaminates through their mouth or nose.

However, face masks that provide protection from airborne contaminants often require proper fitting, which can be difficult if the user is not a trained medical professional. Particularly, many face masks require a user to tie a fastening portion behind their head, or properly tighten the wire or metal strip above a bridge of the user's nose. This is problematic as face mask use outside of a hospital or medical environment (where wearers are accustomed or trained to don such protective apparel), such as in day-to-day life, including while at work, can result in improperly fitted masks, which greatly reduces their effectiveness. Furthermore, it is also desirable, particularly in a workplace type setting to utilize disposable face masks, as it minimizes contamination being brought in and out of the workplace. However, this results in a user having to re-fit their mask at least once per shift.

Moreover, it is difficult to store large quantities of face masks, as the filtration quality tends to degrade with age. However, it is also difficult to produce large quantities of existing filtration face masks quickly, as the line speeds are normally quite slow, resulting in only about 160 masks per minute or less being produced. Therefore, it can be difficult for employers to provide large quantities of disposable masks.

Therefore, it would be advantageous to provide a face mask that solves one or more of the above problems. In one aspect, it would be beneficial to provide a face mask that fits a majority of users without requiring the user to adjust the facemask. It would also be an advantage to provide a face mask that can be produced quickly. Furthermore, it would be beneficial to provide a face mask that has a high level of filtration, such as filtering about 90% or more of airborne particles, without requiring the use of specialty pre-made components.

SUMMARY OF THE INVENTION

The present disclosure is generally directed to a barrier face mask that includes a mask body and at least one elastic strap attached to a first side and a second side of the mask body. The mask body is formed from one or more nonwoven web layers, and includes a seamless filter portion, an upper elastic portion, and a lower elastic portion.

In one aspect, the mask body includes at least two layers, where one or more of the layers is formed from a meltblown nonwoven web. Additionally or alternatively, in an aspect, the meltblown nonwoven web has been electrostatically treated. In one aspect, the mask body includes a spunbond layer and a meltblown nonwoven layer. In a further aspect, the mask body includes a spunbond-meltblown-spunbond layer, and a meltblown nonwoven layer.

In an aspect, the face mask filters 70% or more of particles having a size of 0.65 microns or greater. Furthermore, in one aspect, the face mask exhibits an air permeability according to ASTM D737 of about 20 cfm or greater.

Additionally or alternatively, the upper elastic portion, the lower elastic portion, or both the upper elastic portion and the lower elastic portion are disposed between a first and a second nonwoven layer of the mask body. Furthermore, in an aspect, the upper elastic portion, the lower elastic portion, or both the upper elastic portion and the lower elastic portion are laminated to the one or more nonwoven web layers. In one aspect, the at least one elastic strap is formed from the same elastic as the upper elastic portion, the lower elastic portion, or both the upper elastic portion and the lower elastic portion. Moreover, in one aspect, the face mask includes at least two straps.

In yet a further aspect, the mask body has a length in an extended state of about 200 millimeters to about 350 millimeters. In an additional aspect, the at least one elastic strap has a length in an extended state of about 200 millimeters to about 350 millimeters. Furthermore, in one aspect, the at least one elastic strap has a width in an extended state of about 25 millimeters to about 75 millimeters.

The present disclosure also generally includes a method of forming a face mask. The method includes forming a laminate by unwinding a first nonwoven web, placing one or more elastic members in an upper region, a lower region, or both an upper region and a lower region, unwinding a second nonwoven web, and laminating the first nonwoven web, one or more elastic members, and the second nonwoven web, and attaching one or more straps to a leading edge and a trailing edge of the laminate. In the method, the one or more straps are attached to the laminate during an in-line process.

In one aspect, the method includes cutting the one or more straps from the laminate prior to attaching the straps to the laminate. In one aspect, the second nonwoven web is a meltblown nonwoven web, and the method includes unwinding an untreated meltblown web and subjecting the untreated meltblown web to an electrostatic treatment prior to laminating the meltblown web to the first nonwoven web and the one or more elastic members. Additionally or alternatively, the first nonwoven web is a spunbond nonwoven web or a spunbond-meltblown-spunbond fabric. In one aspect, an adhesive is applied to the one or more elastic members. Moreover, in an aspect, the one or more straps, or both the laminate and the one or more straps are held in a stretched state during lamination, attachment of the one or more straps, or both lamination and attachment of the one or more straps.

Other features and aspects of the present invention are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWING

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the appended figure in which:

FIG. 1 illustrates a side view of one aspect of a face mask according to the present disclosure;

FIG. 2 illustrates a front view of one aspect of a face mask according to the present disclosure;

FIG. 3 illustrates a rear view of one aspect of a face mask according to the present disclosure; and

FIG. 4 illustrates forming a face mask according to one aspect of the present disclosure.

Repeat use of reference characters in the present specification and drawing is intended to represent same or analogous features or elements of the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS Definitions

As used herein, the terms “about,” “approximately,” or “generally,” when used to modify a value, indicates that the value can be raised or lowered by 10% and remain within the disclosed aspect.

As used herein, “fitting a large proportion of users” is based upon anthropometric data for head, face, and neck dimensions according to ISO/TX 19672-2 (2015). For example, an average bigonial diameter of 132.5-144.5 millimeters (mm), an average menton-sellion length of 123 mm to 135 mm, an interpupillary breadth of 65 mm to 71 mm, and an average bitragion chin arc of 295 mm to 315 mm, may generally be relied upon as ranges of an average sized adult head, face, and neck. Thus, as used herein, a face mask according to the present disclosure may properly fit and cover a nose and mouth of about 70% or more of users, such as about 75% or more, such as about 80% or more, such as about 85% or more, such as about 90% or more of users based upon the above average dimensions.

As used herein, the term “fibers” generally refer to elongated extrudates that may be formed by passing a polymer through a forming orifice, such as a die. Unless noted otherwise, the term “fibers” includes discontinuous fibers having a definite length (e.g., stable fibers) and substantially continuous filaments. Substantially filaments may, for instance, have a length much greater than their diameter, such as a length to diameter ratio (“aspect ratio”) greater than about 15,000 to 1, and in some cases, greater than about 50,000 to 1.

As used herein the term “nonwoven web” generally refers to a web having a structure of fibers that are interlaid, but not in an identifiable manner as in a knitted fabric. Examples of suitable nonwoven webs include, but are not limited to, meltblown webs, spunbond webs, bonded carded webs, airlaid webs, coform webs, hydraulically entangled webs, and so forth.

As used herein, the term “spunbond” web generally refers to a nonwoven web containing substantially continuous filaments formed by extruding a molten thermoplastic material from a plurality of fine, usually circular, capillaries of a spinnerette with the diameter of the extruded fibers then being rapidly reduced as by, for example, eductive drawing and/or other well-known spunbonding mechanisms. The production of spunbond webs is described and illustrated, for example, in U.S. Pat. No. 4,340,563 to Appel, et al., U.S. Pat. No. 3,692,618 to Dorschner, et al., U.S. Pat. No. 3,802,817 to Matsuki, et al., U.S. Pat. No. 3,338,992 to Kinney, U.S. Pat. No. 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, U.S. Pat. No. 3,502,538 to Levy, U.S. Pat. No. 3,542,615 to Dobo, et al., and U.S. Pat. No. 5,382,400 to Pike, et al.

As used herein, the term “meltblown” web or facing generally refers to a nonwoven web containing fibers formed by a process in which a molten thermoplastic material is extruded through a plurality of fine, usually circular, die capillaries as molten fibers into converging high velocity gas (e.g., air) streams that attenuate the fibers of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin, et al.

As used herein, the terms “machine direction” or “MD” generally refers to the direction in which a material is produced. The term “cross-machine direction” or “CD” generally refers to the direction perpendicular to the machine direction. Dimensions measured in the cross-machine direction are also referred to as “width” dimension, while dimensions measured in the machine direction are referred to as “length” dimensions.

As used herein the term “extensible” generally refers to a material that stretches or extends in the direction of an applied force (e.g., CD or MD direction) by about 50% or more, in some embodiments about 75% or more, in some embodiments about 100% or more, and in some embodiments, about 200% or more of its relaxed length or width.

As used herein, the term “elastic” generally refers to an extensible material that, upon application of a stretching force, is stretchable in at least one direction (e.g., CD or MD direction), and which upon release of the stretching force, contracts/returns to approximately its original dimension. For example, the stretched material may contract or recover at least about 50%, and even more desirably, at least about 80% of its stretched length. It should be understood that an extensible material may lack recovery properties such that it is considered an “inelastic” material. Materials may be tested for elastic properties using a cyclical testing procedure, such as described below.

DETAILED DESCRIPTION

Reference now will be made in detail to various embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations.

Generally speaking, the present disclosure is directed to a face mask have a tube-shaped design, that does not require a user to tie or otherwise manually attach the straps to don the mask. Particularly the present disclosure has found that by utilizing a mask body that contains a filter portion, an upper elastic portion, and a lower elastic portion, excellent filtration of airborne particles can be achieved by the uninterrupted filter portion, while achieving good fit properties on a large proportion of users due to the upper and lower elastic portions. Furthermore, the present disclosure has also found that, by utilizing one or more elastic straps bonded to the body portion, a tube-shaped face mask (e.g. that complete encircles the head of a user when donned) can be formed that results in a good fit on a large proportion of users without requiring tying or fit-adjustment by the user. Additionally, as the straps encircle the head and are formed from a wide elastic with good comfort properties, such as softness and feel, while retaining good elasticity, it also enables longer-term wear without causing fatigue or discomfort to the head or ears of the wearer.

For instance, referring to FIGS. 1 and 2 , a face mask 100 according to an aspect of the present disclosure is illustrated. The face mask 100 includes a mask body 102 formed from a filter portion 104, an upper elastic portion 106, and a lower elastic portion 108. As will be discussed in greater detail below, the mask body 102 may include two or more layers. Thus, in one aspect, the upper elastic portion 106 may generally be formed by adhering an elastic member to at least one layer of the mask body 102 in an upper region 110 of the mask body 102. Of course, in one aspect, the upper elastic portion 106 may be “sandwiched” between a first layer and a second layer of the mask body 102 (shown and discussed in greater detail in regard to FIG. 4 below). Thus, in such an aspect, the elastic member can form the attachment between the first layer and the second layer of the mask body 102, and, as will be discussed in greater detail below, may be adhered to the first layer and the second layer as known in the art.

Furthermore, in one aspect, one or more of the first layer, the second layer, or both the first layer and the second layer of the mask body 102 may have some elasticity or stretch. In such an aspect, the first and/or second layer of the mask body 102 may be adhered to the elastic member in an extended, or at least partially extended state, in order to provide an upper elastic portion 106 with a gathered orientation, when at least partially relaxed. For instance, as shown in FIGS. 1 and 2 , the upper elastic portion 106 may be attached to the mask body 102 such that the mask body 102 has a gathered orientation when in a relaxed state. Particularly, the present disclosure has found that such an orientation may result in improved fit, and may provide an improved fit for a large variety of users, as the gathered orientation can result in greater contact around the nose and eye portion of the user without requiring the use of a wire or other clip over the bridge of the nose.

Similarly, the present disclosure has found that a lower elastic portion 108 may be formed using an elastic member as described above in regards to the upper elastic portion 106 but may be located in a lower region 112 of the mask body 102, that is opposite the upper region 110. Thus, in one aspect, the lower elastic portion 108. may generally be formed by adhering an elastic member to at least one layer of the mask body 102 in a lower region 112 of the mask body 102. Of course, in one aspect, the lower elastic portion 108 may be “sandwiched” between a first layer and a second layer of the mask body 102 (shown and discussed in greater detail in regard to FIG. 4 below). In such an aspect, the elastic member can form the attachment between the first layer and the second layer of the mask body 102, and, as will be discussed in greater detail below, may be adhered to the first layer and the second layer as known in the art.

Furthermore, as discussed above, in one aspect, one or more of the first layer, the second layer, or both the first layer and the second layer of the mask body 102 may have some elasticity or stretch. In such an aspect, the first and/or second layer of the mask body 102 may be adhered to the elastic member of the lower elastic portion 108 in an extended, or at least partially extended state, in order to provide a lower elastic portion 108 with a gathered orientation. For instance, as shown in FIG. 1 , the lower elastic portion 108 may be attached to the mask body 102 such that the mask body 102 has a gathered orientation when in a relaxed state. Particularly, the present disclosure has found that such an orientation may result in improved fit over a chin and jaw area of a user, and may provide an improved fit for a large variety of users, as the gathered orientation can result in greater contact around the chin and jaw portion of the user without requiring the user to tighten or adjust the closure of the face mask.

Of course, while the above aspect has been generally described as having an elastic member of the upper and lower regions located between two layers of the mask body, it should be understood that, in an alternative aspect, two or more layers of the mask body may be adhered to one another, and the elastic member may be adhered to one or more of those layers. Additionally, in one aspect, the mask body may be formed from a single layer, where at least one side of the layer is adhered to the elastic member of the upper and lower regions. In a further aspect, as will be discussed in greater detail below, the mask body may include more than two layers, and the elastic member of the upper and lower regions may be adhered between any two of the layers or may be adhered to an exterior portion of one or more of the layers.

Nonetheless, referring to FIGS. 1-3 , and as discussed above, the face mask of the present disclosure may also include one or more straps 114 attached to the mask body 102. Particularly, as shown, the strap 114 or straps 114 may be attached to a first side 116 and an opposed second side 118 of the mask body 102. As shown most clearly in FIG. 2 , the first side 116 and/or opposed second side 118 both intersect the top region 110 and bottom region 112. However, while shown in the extended state in FIG. 2 as being a generally square shape, it should be understood that, in a relaxed state, such as generally shown in FIG. 1 , the face mask 100 may have a less uniform shape, while still having a first side 116 and/or opposed second side 118, that intersect the bottom region 112 and top region 110.

In one aspect, the strap(s) 114 may be formed of the same material as the elastic member of the upper elastic portion 106, lower elastic portion 108, or both the upper elastic portion 106 and lower elastic portion 108. Regardless of whether the elastic members of the strap(s) 114, upper region 106, or lower region 108 are the same or different, the elastic member(s) may have a variety of configurations. For example, the width of the individual elastic member(s) may be varied from about 1 millimeter to about 100 millimeters, such as from about 10 millimeters to about 90 millimeters, such as from about 25 millimeters to about 75 millimeters, such as from about 40 millimeters to about 60 millimeters, or any ranges or values therebetween. Particularly, the present disclosure has found that straps having such a width may further improve the comfort of the wearer while maintaining good elastic properties.

Notwithstanding the width of elastic member(s), the elastic member(s) may include a single strand of elastic material or may include several parallel or non-parallel strands of elastic material or may be applied in a rectilinear or curvilinear arrangement. Where the strands are non-parallel, two or more of the strands may intersect or otherwise interconnect within the elastic member(s).

While the elastic member(s) may be formed of any elastic material as known in the art, in one aspect, one or more of the elastic member(s) may include one or more elastic strands composed of a Lycra elastomer available from DuPont, a business having offices in Wilmington, Del. Each elastic strand is may have a linear density of about 600 decitex (dtx) to about 1200 dtx, such as from about 700 dtx to about 1100 dtx, such as from about 800 dtx to about 1000 dtx, or any ranges or values therebetween. Furthermore, in one aspect, the elastic member may include one strand to about 7 strands, such as from 2 strands to about 5 strands, or any ranges or values therebetween.

Nonetheless, the elastic member(s) of the one or more straps 114 may be affixed to the mask body 102 in any of several ways which are known in the art. For example, the elastic members may be ultrasonically bonded, heat and pressure sealed using a variety of bonding patterns, or adhesively bonded to mask body 102 with sprayed or swirled patterns of hotmelt adhesive. Regardless, in one aspect, the strap(s) 114 may be continuous (e.g. extending from the first side 116 to the second side 118 with no seam or tie located therebetween).

While the straps and mask body may be formed according to any of the above, in one aspect, the face mask may have a size that fits a large proportion of users. For instance, in one aspect, the face mask may have a mask body length L1 in a stretched state of about 200 mm to about 350 mm, such as about 225 mm to about 325 mm, such as about 250 mm to about 300 mm, or any ranges or values therebetween. Furthermore, in one aspect, the strap(s) may have a length L2 in an extended state of about 200 mm to about 350 mm, such as about 225 mm to about 325 mm, such as about 250 mm to about 300 mm, or any ranges or values therebetween. Furthermore, the strap(s) may have a width W1 of about 25 mm to about 75 mm, such as about 30 mm to about 70 mm, such as about 35 mm to about 65 mm, such as about 40 mm to about 65 mm. In one aspect having two straps, each strap may have the same width, or may have different widths according to the above discussed widths. Nonetheless, as defined above, the face mask according to the present disclosure may therefore have a shape and size that fits a large proportion of users.

Regardless of the elastic member(s) or straps 114 used, the mask body 102 may be formed of one or more layers as discussed above. Each layer may generally be formed from a nonwoven web, such as a spunbond, meltblown, or coform nonwoven web, a bonded carded web, or a wetlaid web. In one aspect, the mask body 102 includes two layers, however, it should be understood that three layers, or more may also be used. For instance, in one aspect, the mask body 102 includes a spunbond layer and a meltblown layer. However, in a further aspect, the mask body may include a meltblown layer located between two spunbond layers, or alternatively, one or both spunbond layers may instead be formed of a SMS (spunbond-meltblown-spunbond) fabric.

Particularly, the present disclosure has found that a mask including a first layer, and a second layer, where at least one of the first layer and the second layer includes a meltblown web displays excellent filtration properties while maintaining good elastic properties (to maintain proper fit) and good comfort for the wearer. Additionally, without intending to be bound by theory, it is also believed that, as in one aspect, the filtration portion may be exhibit excellent filtration properties as it is uninterrupted by seams or adhesive and may be further improved by subjecting the meltblown layer to one or more corona treatments, as will be discussed in greater detail below. For instance, the present disclosure has found that the face mask may filter at least about 70% or more of airborne particles having a size of about 0.65 microns or greater according to EN 13274-7 (utilizing a Sodium Chloride aerosol have a particle size of 0.65 microns and a velocity of 95 liters/minute over an area of 100 cm), such as about 75% or more, such as bout 80% or more, such as about 85% or more, such as about 90% or more of particles having a size of about 0.65 microns or greater.

Furthermore, the present disclosure has found that the face mask exhibits the excellent filtration properties while maintaining good air permeability through the face mask. For instance, the face mask can exhibit an air permeability measured according to ASTM D737 (2020, measured using a 38 cm² sample and a pressure of 125 Pa) of about 20 cfm or greater, such as about 25 cfm or greater, such as about 30 cfm or greater, such as about 32.5 cfm or greater, such as about 35 cfm or greater, such as about 40 cfm or greater, or any ranges or values therebetween. Therefore, in addition to providing good filtration properties, the face mask according to the present disclosure also provides increased comfort.

Furthermore, in one aspect, one or more of the layers used to form the mask body 102 may have a design printed on an exterior facing portion of the layer or may be formed from colored or patterned fibers which provide a design or pattern to the face mask.

Nonetheless, exemplary polymers that can be used in forming any or each of the two or more nonwoven web(s) can include olefins (e.g., polyethylene and polypropylenes), polyesters (e.g., polybutylene terephthalate, polybutylene naphthalate), polyamides (e.g., nylons), polycarbonates, polyphenylene sulfides, polystyrenes, polyurethanes (e.g., thermoplastic polyurethanes), etc. In one particular aspect, the fibers of the nonwoven web material can include an olefin homopolymer. One suitable olefin homopolymer is a propylene homopolymer having a density of 0.91 grams per cubic centimeter (g/cm3), a melt flow rate of 1200 g/10 minute (230° C., 2.16 kg), a crystallization temperature of 113° C., and a melting temperature of 156° C., and is available as METOCENE MF650X polymer from LyondellBasell Industries in Rotterdam, The Netherlands. Another suitable propylene homopolymer that can be used has a density of 0.905 g/cm3, a melt flow rate of 1300 g/10 minute (230° C., 2.16 kg), and a melting temperature of 165° C., and is available as Polypropylene 3962 from Total Petrochemicals in Houston, Tex. Another suitable polypropylene is available as EXXTRAL™ 3155, available from ExxonMobil Chemical Company of Houston, Tex.

Further, a variety of thermoplastic elastomeric and plastomeric polymers may generally be employed in the nonwoven web material of the present disclosure, such as elastomeric polyesters, elastomeric polyurethanes, elastomeric polyamides, elastomeric copolymers, elastomeric polyolefins, and so forth. In one particular aspect, elastomeric semi-crystalline polyolefins are employed due to their unique combination of mechanical and elastomeric properties. Semi-crystalline polyolefins have or are capable of exhibiting a substantially regular structure. For example, semi-crystalline polyolefins may be substantially amorphous in their undeformed state but form crystalline domains upon stretching. The degree of crystallinity of the olefin polymer may be from about 3% to about 60%, in some aspects from about 5% to about 45%, in some aspects from about 5% to about 30%, and in some aspects, from about 5% and about 15%. Likewise, the semi-crystalline polyolefin may have a latent heat of fusion (

Ht), which is another indicator of the degree of crystallinity, of from about 15 to about 210 Joules per gram (“J/g”), in some aspects from about 20 to about 100 J/g, in some aspects from about 20 to about 65 J/g, and in some aspects, from 25 to about 50 J/g. The semi-crystalline polyolefin may also have a Vicat softening temperature of from about 10

C to about 100

C, in some aspects from about 20

C to about 80

C, and in some aspects, from about 30

C to about 60

C. The semi-crystalline polyolefin may have a melting temperature of from about 20

C to about 120

C, in some aspects from about 35

C to about 90

C, and in some aspects, from about 40

C to about 80

C. The latent heat of fusion (

Hf) and melting temperature may be determined using differential scanning calorimetry (“DSC”) in accordance with ASTM D-3417 as is well known to those skilled in the art. The Vicat softening temperature may be determined in accordance with ASTM D-1525.

Exemplary semi-crystalline polyolefins include polyethylene, polypropylene, as well as their blends and copolymers thereof. In one particular aspect, a polyethylene is employed that is a copolymer of ethylene and an

-olefin, such as a C3-C20

-olefin or C3-C12

-olefin. Suitable

-olefins may be linear or branched (e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired

-olefin comonomers are 1-butene, 1-hexene, and 1-octene. The ethylene content of such copolymers may be from about 60 mole % to about 99 mole %, in some aspects from about 80 mole % to about 98.5 mole %, and in some aspects, from about 87 mole % to about 97.5 mole %. The

-olefin content may likewise range from about 1 mole % to about 40 mole %, in some aspects from about 1.5 mole % to about 15 mole %, and in some aspects, from about 2.5 mole % to about 13 mole %.

The density of the polyethylene may vary depending on the type of polymer employed, but generally ranges from about 0.85 g/cm3 to about 0.96 g/cm3. Polyethylene “plastomers”, for instance, may have a density in the range of from 0.85 g/cm3 to 0.91 g/cm3. Likewise, “linear low density polyethylene” (“LLDPE”) may have a density in the range of from about 0.91 g/cm3 to about 0.94 g/cm3; “low density polyethylene” (“LDPE”) may have a density in the range of from about 0.91 g/cm3 to about 0.94 g/cm3; and “high density polyethylene” (“HDPE”) may have density in the range of from 0.94 g/cm3 to 0.96 g/cm3. Densities may be measured in accordance with ASTM 1505.

Particularly suitable polyethylene copolymers are those that are “linear” or “substantially linear.” The term “substantially linear” means that, in addition to the short chain branches attributable to comonomer incorporation, the ethylene polymer also contains long chain branches in the polymer backbone. “Long chain branching” refers to a chain length of at least 6 carbons. Each long chain branch may have the same comonomer distribution as the polymer backbone and be as long as the polymer backbone to which it is attached. Preferred substantially linear polymers are substituted with from 0.01 long chain branch per 1000 carbons to 1 long chain branch per 1000 carbons, and in some aspects, from 0.05 long chain branch per 1000 carbons to 1 long chain branch per 1000 carbons. In contrast to the term “substantially linear”, the term “linear” means that the polymer lacks measurable or demonstrable long chain branches. That is, the polymer is substituted with an average of less than 0.01 long chain branch per 1000 carbons.

The density of a linear ethylene/

-olefin copolymer is a function of both the length and amount of the

-olefin. That is, the greater the length of the

-olefin and the greater the amount of

-olefin present, the lower the density of the copolymer. Although not necessarily required, linear polyethylene “plastomers” are particularly desirable in that the content of

-olefin short chain branching content is such that the ethylene copolymer exhibits both plastic and elastomeric characteristics—i.e., a “plastomer.” Because polymerization with

-olefin comonomers decreases crystallinity and density, the resulting plastomer normally has a density lower than that of polyethylene thermoplastic polymers (e.g., LLDPE), but approaching and/or overlapping that of an elastomer. For example, the density of the polyethylene plastomer may be 0.91 g/cm3 or less, in some aspects, from about 0.85 g/cm3 to about 0.88 g/cm3, and in some aspects, from about 0.85 g/cm3 to about 0.87 g/cm3. Despite having a density similar to elastomers, plastomers generally exhibit a higher degree of crystallinity and may be formed into pellets that are non-adhesive and relatively free flowing.

The distribution of the

-olefin comonomer within a polyethylene plastomer is typically random and uniform among the differing molecular weight fractions forming the ethylene copolymer. This uniformity of comonomer distribution within the plastomer may be expressed as a comonomer distribution breadth index value (“CDBI”) of 60 or more, in some aspects 80 or more, and in some aspects, 90 or more. Further, the polyethylene plastomer may be characterized by a DSC melting point curve that exhibits the occurrence of a single melting point peak occurring in the region of 50 to 110

C (second melt rundown).

Suitable plastomers for use in the present disclosure are ethylene-based copolymer plastomers available under the designation EXACT™ from ExxonMobil Chemical Company of Houston, Tex. Other suitable polyethylene-based plastomers are available under the designation ENGAGE™ and AFFINITY™ from Dow Chemical Company of Midland, Mich. An additional suitable polyethylene-based plastomer is an olefin block copolymer available from Dow Chemical Company of Midland, Mich. under the trade designation INFUSE™, such as INFUSE™ 9807. A polyethylene that can be used in the fibers of the present disclosure is DOW™ 61800.41. Still other suitable ethylene polymers are available from The Dow Chemical Company under the designations DOWLEX™ (LLDPE), ASPUN™ (LLDPE), and ATTANE™ (ULDPE). Other suitable ethylene polymers are described in U.S. Pat. No. 4,937,299 to Ewen et al.; U.S. Pat. No. 5,218,071 to Tsutsui et al.; U.S. Pat. No. 5,272,236 to Lai, et al.; and U.S. Pat. No. 5,278,272 to Lai, et al., which are incorporated herein in their entirety by reference thereto for all purposes.

Of course, the present disclosure is by no means limited to the use of ethylene polymers. For instance, propylene polymers may also be suitable for use as a semi-crystalline polyolefin. Suitable plastomeric propylene polymers may include, for instance, copolymers or terpolymers of propylene include copolymers of propylene with an

-olefin (e.g., C3-C20), such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer content of the propylene polymer may be about 35 wt. % or less, in some aspects from about 1 wt. % to about 20 wt. %, and in some aspects, from about 2 wt. % to about 10 wt. %. Preferably, the density of the polypropylene (e.g., propylene/

-olefin copolymer) may be 0.91 grams per cubic centimeter (g/cm3) or less, in some aspects, from 0.85 to 0.88 g/cm3, and in some aspects, from 0.85 g/cm3 to 0.87 g/cm3. Suitable propylene-based copolymer plastomers are commercially available under the designations VISTAMAXX™ (e.g., 2330, 6202, and 6102), a propylene-ethylene copolymer-based plastomer from ExxonMobil Chemical Co. of Houston, Tex.; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMER™ available from Mitsui Petrochemical Industries; and VERSIFY™ available from Dow Chemical Co. of Midland, Mich. Other examples of suitable propylene polymers are described in U.S. Pat. No. 6,500,563 to Datta, et al.; U.S. Pat. No. 5,539,056 to Yang, et al.; and U.S. Pat. No. 5,596,052 to Resconi, et al., which are incorporated herein in their entirety by reference thereto for all purposes.

Any of a variety of known techniques may generally be employed to form the semi-crystalline polyolefins. For instance, olefin polymers may be formed using a free radical or a coordination catalyst (e.g., Ziegler-Natta). Preferably, the olefin polymer is formed from a single-site coordination catalyst, such as a metallocene catalyst. Such a catalyst system produces ethylene copolymers in which the comonomer is randomly distributed within a molecular chain and uniformly distributed across the different molecular weight fractions. Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. No. 5,571,619 to McAlpin et al.; U.S. Pat. No. 5,322,728 to Davis et al.; U.S. Pat. No. 5,472,775 to Obijeski et al.; U.S. Pat. No. 5,272,236 to Lai et al.; and U.S. Pat. No. 6,090,325 to Wheat, et al., which are incorporated herein in their entirety by reference thereto for all purposes. Examples of metallocene catalysts include bis(n-butylcyclopentadienyl)titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium dichloride, bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride, isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene, titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride, and so forth. Polymers made using metallocene catalysts typically have a narrow molecular weight range. For instance, metallocene-catalyzed polymers may have polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching distribution, and controlled isotacticity.

The melt flow index (MI) of the semi-crystalline polyolefins may generally vary, but is typically in the range of about 0.1 grams per 10 minutes to about 100 grams per 10 minutes, in some aspects from about 0.5 grams per 10 minutes to about 30 grams per 10 minutes, and in some aspects, about 1 to about 10 grams per 10 minutes, determined at 190

C. The melt flow index is the weight of the polymer (in grams) that may be forced through an extrusion rheometer orifice (0.0825-inch diameter) when subjected to a force of 5000 grams in 10 minutes at 190

C, and may be determined in accordance with ASTM Test Method D1238-E.

While the elastomer has been thus far generally discussed as a component of a fiber for a nonwoven, it should be understood that the fiber may contain both a core layer and a skin layer, where the core layer and the skin layer may contain the same elastomer(s) or a different elastomer or elastomer(s). For instance, in one aspect, the core layer may contain a polyethylene based copolymer elastomer as discussed above (e.g., INFUSE™), whereas the skin layer may contain a polypropylene based copolymer elastomer (e.g., VERSIFY™).

Additionally or Alternatively, the core layer and skin layer may each be formed from either a propylene based copolymer or an ethylene based copolymer (or any other elastomer discussed above), however, the core layer is formed from an elastomer having a “medium” to “high” molecular weight, whereas the skin layer is formed from an elastomer having a “low” molecular weight. For instance, in one aspect, the “medium” to “high” molecular weight elastomer can have a number average molecular weight of about 10,000 g/mol to about 70,000 g/mol, such as about 12,500 g/mol to about 67,500 g/mol, such as about 15,000 g/mol to about 65,000, such as about 17,500 g/mol to about 62,500 g/mol, such as about 20,000 g/mol to about 60,000 g/mol, or any ranges or values therebetween. Furthermore, a “low” molecular weight elastomer according to the present disclosure may have a number average molecular weight of about 1,000 g/mol to about 10,000 g/mol, such as about 2,000 g/mol to about 9,000 g/mol, such as about 3,000 g/mol to about 8,000 g/mol, such as about 4,000 g/mol to about 7,000 g/mol, such as about 4,500 g/mol to about 6,500 g/mol or any ranges or values therebetween.

For instance, in one aspect, a ratio of the average molecular weight of the total elastomer or elastomers in the core layer to a ratio of the average molecular weight of the total elastomer or elastomers in the skin layer may be from about 10:1 to about 1.1:1, such as about 7.5:1 to about 1.5:1, such as about 5:1 to about 2:1, or any ranges or valued therebetween. Without wishing to be bound by theory, the present disclosure has found that by using a lower molecular weight elastomer in the skin layer as compared to the core layer, an increase in tension forces upon stretching which are normally exhibited when using a non-blocking skin layer may be avoided. Thus, in one aspect, a lower molecular weight elastomer is used in the skin layer, which can further improve the elastic efficiency of the composition according to the present disclosure.

Of course, other thermoplastic polymers may also be used to form nonwoven web material. For instance, a substantially amorphous block copolymer may be employed that has at least two blocks of a monoalkenyl arene polymer separated by at least one block of a saturated conjugated diene polymer. The monoalkenyl arene blocks may include styrene and its analogues and homologues, such as o-methyl styrene; p-methyl styrene; p-tert-butyl styrene; 1,3 dimethyl styrene p-methyl styrene; etc., as well as other monoalkenyl polycyclic aromatic compounds, such as vinyl naphthalene; vinyl anthrycene; and so forth. Preferred monoalkenyl arenes are styrene and p-methyl styrene. The conjugated diene blocks may include homopolymers of conjugated diene monomers, copolymers of two or more conjugated dienes, and copolymers of one or more of the dienes with another monomer in which the blocks are predominantly conjugated diene units. Preferably, the conjugated dienes contain from 4 to 8 carbon atoms, such as 1,3 butadiene (butadiene); 2-methyl-1,3 butadiene; isoprene; 2,3 dimethyl-1,3 butadiene; 1,3 pentadiene (piperylene); 1,3 hexadiene; and so forth.

The amount of monoalkenyl arene (e.g., polystyrene) blocks may vary, but typically constitute from about 8 wt. % to about 55 wt. %, in some aspects from about 10 wt. % to about 35 wt. %, and in some aspects, from about 25 wt. % to about 35 wt. % of the copolymer. Suitable block copolymers may contain monoalkenyl arene endblocks having a number average molecular weight from about 5,000 to about 35,000 and saturated conjugated diene midblocks having a number average molecular weight from about 20,000 to about 170,000. The total number average molecular weight of the block polymer may be from about 30,000 to about 250,000.

Particularly suitable thermoplastic elastomeric block copolymers are available from Kraton Polymers LLC of Houston, Tex. under the trade name KRATON™. KRATON™ polymers include styrene-diene block copolymers, such as styrene-butadiene, styrene-isoprene, styrene-butadiene-styrene, and styrene-isoprene-styrene. KRATON™ polymers also include styrene-olefin block copolymers formed by selective hydrogenation of styrene-diene block copolymers. Examples of such styrene-olefin block copolymers include styrene-(ethylene-butylene), styrene-(ethylene-propylene), styrene-(ethylene-butylene)-styrene, styrene-(ethylene-propylene)-styrene, styrene-(ethylene-butylene)-styrene-(ethylene-butylene), styrene-(ethylene-propylene)-styrene-(ethylene-propylene), and styrene-ethylene-(ethylene-propylene)-styrene. These block copolymers may have a linear, radial or star-shaped molecular configuration. Specific KRATON™ block copolymers include those sold under the brand names G 1652, G 1657, G 1730, MD6673, MD6703, MD6716, and MD6973. Various suitable styrenic block copolymers are described in U.S. Pat. Nos. 4,663,220, 4,323,534, 4,834,738, 5,093,422 and 5,304,599, which are hereby incorporated in their entirety by reference thereto for all purposes. Other commercially available block copolymers include the S-EP-S and S-E-E-P-S elastomeric copolymers available from Kuraray Company, Ltd. of Okayama, Japan, under the trade designation SEPTON™. Still other suitable copolymers include the S-I-S and S-B-S elastomeric copolymers available from Dexco Polymers of Houston, Tex. under the trade designation VECTOR™. Also suitable are polymers composed of an A-B-A-B tetrablock copolymer, such as discussed in U.S. Pat. No. 5,332,613 to Taylor, et al., which is incorporated herein in its entirety by reference thereto for all purposes. An example of such a tetrablock copolymer is a styrene-poly(ethylene-propylene)-styrene-poly(ethylene-propylene) (“S-EP-S-EP”) block copolymer.

Nonetheless, while elastomeric polymers have thus far been described, a non-elastomeric polyolefin material, either alone or in combination with one or more of the above elastomers may be used in the skin layer, the core layer, or both the skin and core layer. For instance, when using a non-elastomeric polyolefin material, a non-blocking skin layer may be formed that does not inhibit the elastic efficiency of the composition. Thus, in one aspect, the non-elastomeric polyolefin may include generally inelastic polymers, such as conventional polyolefins, (e.g., polyethylene), low density polyethylene (LDPE), Ziegler-Natta catalyzed linear low density polyethylene (LLDPE), etc.), ultra low density polyethylene (ULDPE), polypropylene, polybutylene, etc.; polytetrafluoroethylene; polyesters, e.g., polyethylene terephthalate (PET), etc.; polyvinyl acetate; polyvinyl chloride acetate; polyvinyl butyral; acrylic resins, e.g., polyacrylate, polymethylacrylate, polymethylmethacrylate, etc.; polyamides, e.g., nylon; polyvinyl chloride; polyvinylidene chloride; polystyrene; polyvinyl alcohol; polyurethanes; polylactic acid; copolymers and mixtures thereof; and so forth. For instance, the skin layer(s) can include an LLDPE available from Dow Chemical Co. of Midland, Mich., such as DOWLEX™ 2517 or DOWLEX™ 2047, or a combination thereof, or Westlake Chemical Corp. of Houston, Tex. Furthermore, in one aspect, the non-blocking polyolefin material may be other suitable ethylene polymers, such as those available from The Dow Chemical Company under the designations ASPUN™ (LLDPE) and ATTANE™ (ULDPE).

A single polymer as discussed above can be used to form the fibers from which the nonwoven web material is comprised, and when utilized, can be utilized in amount up to 100 wt. % based on the total weight of the nonwoven web material, such as from about 75 wt. % to about 99 wt. %, such as from about 80 wt. % to about 98 wt. %, such as from about 85 wt. % to about 95 wt. %. However, in other aspects, the nonwoven web material can include two or more polymers from the polymers discussed above. For instance, monocomponent fibers from which the nonwoven web material can include fibers formed from an olefin homopolymer in an amount ranging from about 5 wt. % to about 80 wt. %, such as from about 10 wt. % to about 75 wt. %, such as from about 15 wt. % to about 70 wt. %, based on the total weight of the nonwoven web material. Meanwhile, the fibers can also include a derivative of an olefin polymer. For instance, the nonwoven web material can include an elastomeric semi-crystalline polyolefin or “plastomer” (e.g., an ethylene/α-olefin copolymer, a propylene/α-olefin copolymer, or a combination thereof); a thermoplastic elastomeric block copolymer; or a combination thereof in an amount ranging from about 20 wt. % to about 95 wt. %, such as from about 25 wt. % to about 90 wt. %, such as from about 30 wt. % to about 85 wt. % based on the total weight of the nonwoven web material.

In additional aspects, the fibers from which the nonwoven web material is formed can be multicomponent and can have a sheath-core arrangement or side-by-side arrangement. For instance, in a sheath-core multicomponent fiber arrangement, the sheath can include a blend of a polypropylene and a polypropylene-based plastomer, (e.g., VISTAMAXX™), while the core can include a blend of a polyethylene and a polyethylene-based plastomer (e.g., INFUSE™). On the other hand, the sheath can include a blend of a polyethylene and a polyethylene-based plastomer (e.g., INFUSE™), while the core can include a blend of a polypropylene and a polypropylene-based plastomer, (e.g., VISTAMAXX™). Further, in still other aspects, the core can include 100% of a polyethylene or a polypropylene homopolymer.

For instance, in some aspects, the fibers from which the nonwoven web material is formed can have a sheath-core arrangement where the sheath can include from about 20 wt. % to about 90 wt. %, such as from about 25 wt. % to about 80 wt. %, such as from about 30 wt. % to about 70 wt. % of an olefin homopolymer (e.g., polypropylene or polyethylene) based on the total weight of the sheath component of the multicomponent fiber. Meanwhile, the sheath can also include from about 10 wt. % to about 80 wt. %, such as from about 20 wt. % to about 75 wt. %, such as from about 30 wt. % to about 70 wt. % of an olefin-based plastomer (e.g., a polypropylene-based plastomer or an ethylene-based plastomer) based on the total weight of the sheath component of the multicomponent fiber.

In addition, the core can include from about 30 wt. % to about 100 wt. %, such as from about 40 wt. % to about 95 wt. %, such as from about 50 wt. % to about 90 wt. % of an olefin homopolymer (e.g., polypropylene or polyethylene) based on the total weight of the core component of the multicomponent fiber. Further, the core can include from about 0 wt. % to about 70 wt. %, such as from about 5 wt. % to about 60 wt. %, such as from about 10 wt. % to about 50 wt. % of an olefin-based plastomer (e.g., a polypropylene-based plastomer or an ethylene-based plastomer) based on the total weight of the core component of the fiber.

Further, the weight percentage of the sheath can range from about 10 wt. % to about 70 wt. %, such as from about 15 wt. % to about 65 wt. %, such as from about 20 wt. % to about 60 wt. %, based on the total weight of the fiber. Meanwhile, the weight percentage of the core can range from about 30 wt. % to about 90 wt. %, such as from about 35 wt. % to about 85 wt. %, such as from about 40 wt. % to about 80 wt. % based on the total weight of the fiber.

In addition, the fibers from which the nonwoven web material is formed can have a side-by-side arrangement where two fibers are coextruded adjacent each other. In such an aspect, the first side can include a polyethylene and a polyethylene-based plastomer, while the second side can include a polypropylene and a polypropylene-based plastomer. The polyethylene can be present in the first side in an amount ranging from about 30 wt. % to about 90 wt. %, such as from about 35 wt. % to about 80 wt. %, such as from about 40 wt. % to about 70 wt. % based on the total weight of the first side. Meanwhile, the polyethylene-based plastomer can be present in the first side in an amount ranging from about 20 wt. % to about 80 wt. %, such as from about 25 wt. % to about 70 wt. %, such as from about 30 wt. % to about 60 wt. % based on the total weight of the first side. In addition, the polypropylene can be present in the second side in an amount ranging from about 30 wt. % to about 90 wt. %, such as from about 35 wt. % to about 80 wt. %, such as from about 40 wt. % to about 70 wt. % based on the total weight of the second side. Meanwhile, the polypropylene-based plastomer can be present in the second side in an amount ranging from about 20 wt. % to about 80 wt. %, such as from about 25 wt. % to about 70 wt. %, such as from about 30 wt. % to about 60 wt. % based on the total weight of the second side.

With such fiber configurations as those discussed above, in some aspects, a propylene-ethylene copolymer can be utilized in either the sheath and/or the core or the first side and/or the second side to act as a compatibilizer and enhance bonding between the sheath and core. For instance, the propylene-ethylene copolymer can be present in the sheath in an amount ranging from about 0.5 wt. % to about 20 wt. %, such as from about 1 wt. % to about 15 wt. %, such as from about 2 wt. % to about 10 wt. % based on the total weight of the sheath. Alternatively, the propylene-ethylene copolymer can be present in the core in an amount ranging from about 0.5 wt. % to about 20 wt. %, such as from about 1 wt. % to about 15 wt. %, such as from about 2 wt. % to about 10 wt. % based on the total weight of the core.

Other additives may also be incorporated into the nonwoven web material, such as melt stabilizers, processing stabilizers, heat stabilizers, light stabilizers, antioxidants, heat aging stabilizers, whitening agents, antiblocking agents, viscosity modifiers, etc. Viscosity modifiers may also be employed, such as polyethylene wax (e.g., EPOLENE™ C-10 from Eastman Chemical). Phosphite stabilizers (e.g., IRGAFOS available from Ciba Specialty Chemicals of Tarrytown, N.Y. and DOVERPHOS available from Dover Chemical Corp. of Dover, Ohio) are exemplary melt stabilizers. In addition, hindered amine stabilizers (e.g., CHIMASSORB available from Ciba Specialty Chemicals) are exemplary heat and light stabilizers. Further, hindered phenols are commonly used as an antioxidant in the production of films. Some suitable hindered phenols include those available from Ciba Specialty Chemicals of under the trade name IRAGANOX™, such as IRGANOX™ 1076, 1010, or E 201. When employed, such additives (e.g., antioxidant, stabilizer, etc.) may each be present in an amount from about 0.001 wt. % to about 25 wt. %, in some aspects, from about 0.005 wt. % to about 20 wt. %, and in some aspects, from 0.01 wt. % to about 15 wt. % of the nonwoven web material.

If desired, a fatty acid derivative may also be employed in the polymer composition, such as in a blend of ductile and rigid polymers, to help achieve the desired degree of ductility. Suitable fatty acid derivatives for use in the composition may include, for instance, fatty acid amides, fatty acid esters, fatty acid salts, and so forth. In one particular embodiment, for example, the fatty acid derivative may be a fatty acid amide. The fatty acid amide may be any suitable amide compound derived from the reaction between a fatty acid and ammonia or an amine-containing compound (e.g., a compound containing a primary amine group or a secondary amine group). The fatty acid may be any suitable fatty acid, such as a saturated or unsaturated C₈-C₂₈ fatty acid or a saturated or unsaturated C₁₂-C₂₈ fatty acid. In certain embodiments, the fatty acid may be erucic acid (i.e., cis-13-docosenoic acid), oleic acid (i.e., cis-9-octadecenoic acid), stearic acid (octadecanoic acid), behenic acid (i.e., docosanoic acid), arachic acid (i.e., arachidinic acid or eicosanoic acid), palmitic acid (i.e., hexadecanoic acid), and mixtures or combinations thereof. The amine-containing compound can be any suitable amine-containing compound, such as fatty amines (e.g., stearylamine or oleylamine), ethylenediamine, 2,2′-iminodiethanol, and 1,1′-iminodipropan-2-ol.

More particularly, the fatty acid amide may be a fatty acid amide having the structure of one of Formulae (I)-(V):

wherein,

R₁₃, R₁₄, R₁₅, R₁₆, and R₁₈ are independently selected from C₇-C₂₇ alkyl groups and C₇-C₂₇ alkenyl groups, and in some embodiments, C₁₁-C₂₇ alkyl groups and C₁₁-C₂₇ alkenyl groups;

R₁₇ is selected from C₈-C₂₈ alkyl groups and C₈-C₂₈ alkenyl groups, and in some embodiments, C₁₂-C₂₈ alkyl groups and C₁₂-C₂₈ alkenyl groups; and

R₁₉ is —CH₂CH₂OH or —CH₂CH(CH₃)OH.

For example, the fatty acid amide may have the structure of Formula (I), where R₁₃ is —CH₂(CH₂)₁₀CH═CH(CH₂)₇CH₃ (erucamide), —CH₂(CH₂)₆CH═CH(CH₂)₇CH₃ (oleamide), —CH₂(CH₂)₁₅CH₃, —CH₂(CH₂)₁₉CH₃, or -CH₂(CH₂)₁₇CH₃. In other embodiments, the fatty acid amide may have the structure of Formula (II) where R₁₄ is —CH₂(CH₂)₁₀CH═CH(CH₂)₇CH₃ and R₁₅ is —CH₂(CH₂)₁₅CH₃, or where R₁₄ is —CH₂(CH₂)₆CH═CH(CH₂)₇CH₃ and R₁₅ is —CH₂(CH₂)₁₃CH₃. Likewise, in yet other embodiments, the fatty acid amide may have the structure of Formula (III) where R₁₆ is CH₂(CH₂)₁₅CH₃ or —CH₂(CH₂)₆CH═CH(CH₂)₇CH₃. The composition may also contain a mixture of two or more such fatty acid amides.

If desired, fatty acid esters may also be employed. Fatty acid esters may be obtained by oxidative bleaching of a crude natural wax and subsequent esterification of a fatty acid with an alcohol. The fatty acid may be a C₈-C₂₈ fatty acid or a saturated or unsaturated C₁₂-C₂₈ fatty acid, such as described above. The alcohol may have 1 to 4 hydroxyl groups and 2 to 20 carbon atoms. When the alcohol is multifunctional (e.g., 2 to 4 hydroxyl groups), a carbon atom number of 2 to 8 is particularly desired. Particularly suitable multifunctional alcohols may include dihydric alcohol (e.g., ethylene glycol, propylene glycol, butylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and 1,4-cyclohexanediol), trihydric alcohol (e.g., glycerol and trimethylolpropane), tetrahydric alcohols (e.g., pentaerythritol and erythritol), and so forth. Aromatic alcohols may also be suitable, such as o-, m- and p-tolylcarbinol, chlorobenzyl alcohol, bromobenzyl alcohol, 2,4-dimethylbenzyl alcohol, 3,5-dimethylbenzyl alcohol, 2,3,5-cumobenzyl alcohol, 3,4,5-trimethylbenzyl alcohol, p-cuminyl alcohol, 1,2-phthalyl alcohol, 1,3-bis(hydroxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, pseudocumenyl glycol, mesitylene glycol and mesitylene glycerol. Fatty acid salts may also be employed, such as those formed by saponification of a fatty acid to neutralize excess carboxylic acids and form a metal salt. Saponification may occur with a metal hydroxide, such as an alkali metal hydroxide (e.g., sodium hydroxide) or alkaline earth metal hydroxide (e.g., calcium hydroxide). The resulting fatty acid salt typically includes an alkali metal (e.g., sodium, potassium, lithium, etc.) or alkaline earth metal (e.g., calcium, magnesium, etc.).

Regardless of the polymer(s) selected, the material can be formed into monocomponent or multicomponent fibers and extruded or spun to form a nonwoven web used in a fabric of the present disclosure. Monocomponent fibers can be formed from a polymer or a blend of polymers as well as any optional components, which are compounded and then extruded from a single extruder. Meanwhile, multicomponent fibers can be formed from two or more polymers (e.g., bicomponent fibers) extruded from separate extruders, where one or more of the polymers can be compounded with a tackifier, although this is not required when one of the polymers exhibits inherent tackiness, such as VISTAMAXX™ polymers and INFUSE™ polymers. The polymers may be arranged in substantially constantly positioned distinct zones across the cross-section of the fibers. The components may be arranged in any desired configuration, such as sheath-core, side-by-side, pie, island-in-the-sea, three island, bull's eye, or various other arrangements known in the art, and so forth. Various methods for forming multicomponent fibers are described in U.S. Pat. No. 4,789,592 to Taniguchi et al. U.S. Pat. No. 5,336,552 to Strack et al., U.S. Pat. No. 5,108,820 to Kaneko, et al., U.S. Pat. No. 4,795,668 to Kruege, et al., U.S. Pat. No. 5,382,400 to Pike, et al., U.S. Pat. No. 5,336,552 to Strack, et al., and U.S. Pat. No. 6,200,669 to Marmon, et al., which are incorporated herein in their entirety by reference thereto for all purposes. Multicomponent fibers having various irregular shapes may also be formed, such as described in U.S. Pat. No. 5,277,976 to Hogle, et al., U.S. Pat. No. 5,162,074 to Hills, U.S. Pat. No. 5,466,410 to Hills, U.S. Pat. No. 5,069,970 to Largman, et al., and U.S. Pat. No. 5,057,368 to Largman, et al., which are incorporated herein in their entirety by reference thereto for all purposes. In addition, hollow fibers are also contemplated by the present disclosure, and such fibers can reduce the amount of polymer required, as well as the basis weight of the resulting nonwoven web material.

Furthermore, after formation, the one or more of the nonwoven web layers may be post-bonded. A patterned bonding technique (e.g., thermal point bonding, ultrasonic bonding, etc.) is generally used in which the nonwoven web material is supplied to a nip defined by at least one patterned roll. Thermal point bonding, for instance, typically employs a nip formed between two rolls, at least one of which is patterned. Ultrasonic bonding, on the other hand, typically employs a nip formed between a sonic horn and a patterned roll. Regardless of the technique chosen, the patterned roll contains a plurality of raised bonding elements to bond the nonwoven web material.

The size of the bonding elements may be specifically tailored to facilitate the formation of apertures in the nonwoven web material and enhance bonding between the fibers contained in the nonwoven web material. For example, the length dimension of the bonding elements may be from about 300 to about 5000 micrometers, in some aspects from about 500 to about 4000 micrometers, and in some aspects, from about 1000 to about 2000 micrometers. The width dimension of the bonding elements may likewise range from about 20 to about 500 micrometers, in some aspects from about 40 to about 200 micrometers, and in some aspects, from about 50 to about 150 micrometers. In addition, the “element aspect ratio” (the ratio of the length of an element to its width) may range from about 2 to about 100, in some aspects from about 4 to about 50, and in some aspects, from about 5 to about 20.

The pattern of the bonding elements is generally selected so that the nonwoven web material has a total bond area of less than about 50% (as determined by conventional optical microscopic methods), in some aspects, less than about 40%, and in some aspects, less than about 25%. The bond density is also typically greater than about 50 bonds per square inch, and in some aspects, from about 75 to about 500 pin bonds per square inch. One suitable bonding pattern for use in the present disclosure is known as an “S-weave” pattern and is described in U.S. Pat. No. 5,964,742 to McCormack, et al., which is incorporated herein in its entirety by reference thereto for all purposes. S-weave patterns typically have a bonding element density of from about 50 to about 500 bonding elements per square inch, and in some aspects, from about 75 to about 150 bonding elements per square inch. Another suitable bonding pattern is known as the “rib-knit” pattern and is described in U.S. Pat. No. 5,620,779 to Levy, et al., which is incorporated herein in its entirety by reference thereto for all purposes. Rib-knit patterns typically have a bonding element density of from about 150 to about 400 bonding elements per square inch, and in some aspects, from about 200 to about 300 bonding elements per square inch Yet another suitable pattern is the “wire weave” pattern, which has a bonding element density of from about 200 to about 500 bonding elements per square inch, and in some aspects, from about 250 to about 350 bonding elements per square inch. Other bond patterns that may be used in the present disclosure are described in U.S. Pat. No. 3,855,046 to Hansen et al.; U.S. Pat. No. 5,962,112 to Haynes et al.; U.S. Pat. No. 6,093,665 to Sayovitz et al.; D375,844 to Edwards, et al.; D428,267 to Romano et al.; and D390,708 to Brown, which are incorporated herein in their entirety by reference thereto for all purposes.

The selection of an appropriate bonding temperature (e.g., the temperature of a heated roll) will help melt and/soften nonwoven web material at regions adjacent to the bonding elements. The softened nonwoven web material may then flow and become displaced during bonding, such as by pressure exerted by the bonding elements.

To achieve bond formation without substantially softening the polymer(s) of the nonwoven web material, the bonding temperature and pressure may be selectively controlled. For example, one or more rolls may be heated to a surface temperature of from about 50° C. to about 160° C., in some aspects from about 60° C. to about 140° C., and in some aspects, from about 70° C. to about 120° C. Likewise, the pressure exerted by rolls (“nip pressure”) during thermal bonding may range from about 75 to about 600 pounds per linear inch (about 1339 to about 10,715 kilograms per meter), in some aspects from about 100 to about 400 pounds per linear inch (about 1786 to about 7143 kilograms per meter), and in some aspects, from about 120 to about 200 pounds per linear inch (about 2143 to about 3572 kilograms per meter). Of course, the residence time of the materials may influence the particular bonding parameters employed.

Notwithstanding the polymers or formation method selected, the filter portion of the mask body having two or more layers may have a basis weight ranging from about 5 gsm (i.e., grams per square meter) to about 100 gsm. For example, the seamless sheet material may of the filter portion may have a basis weight ranging from about 10 gsm to about 75 gsm, such as about 15 gsm to about 70 gsm, such as about 20 gsm to about 60 gsm, such as about 25 gsm to about 50 gsm, or any ranges or values therebetween.

Regardless of the material selected, the upper elastic portion, lower elastic portion, first mask body layer, and second mask body layer may be laminated together. Lamination may be accomplished using a variety of techniques, such as by adhesive bonding, thermal point bonding, ultrasonic bonding, etc. The particular bond pattern is not critical to the present invention. One suitable bond pattern, for instance, is known as an “S-weave” pattern and is described in U.S. Pat. No. 5,964,742 to McCormack, et al. Another suitable bonding pattern is known as the “rib-knit” pattern and is described in U.S. Pat. No. 5,620,779 to Levy, et al. Yet another suitable pattern is the “wire weave” pattern, which bond density of from about 200 to about 500 bond sites per square inch, and in some embodiments, from about 250 to about 350 bond sites per square inch. Of course, other bond patterns may also be used, such as described in U.S. Pat. No. 3,855,046 to Hansen et al.; U.S. Pat. No. 5,962,112 to Haynes et al.; U.S. Pat. No. 6,093,665 to Sayovitz et al.; D375,844 to Edwards, et al.; D428,267 to Romano et al.; and D390,708 to Brown. Furthermore, a bond pattern may also be employed that, similar to the spunbond web described above, contains bond regions that are generally oriented in the machine direction and have a size, aspect ratio, and/or arrangement such as described above. For example, the bond regions may have an aspect ratio of from about 2 to about 100, in some embodiments from about 4 to about 50, and in some embodiments, from about 5 to about 20.

As discussed above, the present disclosure may further include a method of forming a face mask according to the present disclosure. Particularly, the present disclosure has found that a face mask may be formed in a highly efficient manner, and therefore may be able to produce about 400 or more face masks per minute, such as about 450 face masks or more, such as about 500 face masks or more, such as about 550 face masks or more, such as about 600 face masks or more, such as about 650 face masks or more, such as about 700 face masks or more, such as about 750 face masks or more, such as about 800 face masks or more per minute.

Particularly, referring to FIG. 4 , a roll 200 may be unwound in the machine direction (MD) to provide a first layer 202 of the two or more layers that form the mask body 102. Of course, it should be understood that, in one aspect, the layer 202 may also be formed in-line. Nonetheless, as shown, elastic members 204 may be unwound and placed in an upper region 206 and lower region 208 of the first layer 202, such that the elastic members 204 are generally parallel to the machine direction. Of course, as mentioned above, the elastic members 204 may also be applied in a non-linear arrangement. Adhesive 210 may be applied to the elastic members 204, and/or may be applied to first layer 202. Nonetheless, the second layer 212 may be unwound from roll 214 in the machine direction. Of course, as noted above, the second layer 212 may also be formed in-line. Nonetheless, adhesive 210, which may be the same or different as the adhesive applied to the elastic members 204, may be applied to the second layer 212.

In one aspect, the second layer 212 is the meltblown layer, and may undergo a step of electrostatic charging 216. Particularly, as discussed above, the present disclosure has found that, by subjecting the meltblown layer to a corona treatment, the filtration properties of the face mask may be even further improved. However, surprisingly, the present disclosure has found that the meltblown layer may be treated in-line (e.g. after unwinding but prior to lamination). Previously, it had been believed that the corona treatment must be performed prior to winding the web, for instance, during formation of the meltblown web. Thus, in one aspect, the method according to the present disclosure includes taking an untreated meltblown, or SMS, nonwoven web, unwinding the web in-line during the face mask formation process, and subjecting the nonwoven web to an electrostatic treatment during formation of the mask. However, it should be understood that, in one aspect, the meltblown web or SMS web may have been previously electrostatically treated.

Nonetheless, as shown in FIG. 4 , the first layer 202, the elastic members 204, and the second layer 212, may be laminated together during lamination step 218. As previously discussed, in one aspect, first layer 202 and second layer 204 may be stretched during lamination to the elastic members 204 so that the resulting composite is considered “stretch bonded,” resulting in a laminate 218 have a gathered appearance. Regardless, thermal bonding techniques may be employed to laminate the first and second layers to the elastic members. For instance, one or both rolls may be used that contain a plurality of raised bonding elements and/or may be heated. Upon lamination, in one aspect, the layers may be melt fused together at a plurality of bond regions as described above.

In one aspect, as shown in FIG. 4 , the strap(s) 222 may be formed adjacent to the upper region 206 of the mask body 102, and may undergo a slitting step 220, but creating cuts in the laminate generally parallel to the machine direction to separate the one or more straps 222 from the laminate 218 that will form mask body 102. However, it should be understood that, in one aspect, the strap(s) 222 may be formed separately and brought in during seam bonding step 224.

Nonetheless, as shown in the second line of FIG. 4 , the mask body laminate 218 and the strap(s) 222 are combined by one or more seam forming steps 224, where the seams are formed generally perpendicular to the machine direction. As discussed above, the seam forming may include pressure bonding, ultrasonic bonding, thermal bonding, or the like. Nonetheless, as previously discussed, the strap(s) 222 and the laminate 218 may be in a stretched configuration (e.g. stretched in the machine direction by one or more rolls or other stretching mechanism) going into seam forming step 224 in order to yield good extensibility and fit. For instance, the present disclosure has found that such a method may result in a tension in the strap(s) measured according to STM-00070 of about 100 grams*force (gf) or greater, such as about 110 gf or greater, such as about 120 gf or greater, such as about 130 gf or greater, such as about 135 gf or greater, or any ranges or values therebetween.

Regardless of the seam formed, a seam may be formed on a leading edge of each mask, and a trailing edge, of each mask, where the leading edge and/or trailing edge correspond to a first side 116 or a second side 118, as described above in FIGS. 1-3 . In such a manner, the seams may be formed in the laminate as the laminate proceeds through the line in the machine direction.

Furthermore, the present disclosure has found that the seam forming step 224 forms a seam having a bond strength measured according to STM-00090 of about 1 kilogram*force (kgf) or greater, such as about 1.25 kgf or greater, such as about 1.5 kgf or greater, such as about 1.75 kgf or greater, such as about 2 kgf or greater, such as up to about 3 kgf, or any ranges or values therebetween. Particularly, the present disclosure has found that such a bond strength may allow the strap(s) of the face mask to be stretched over the head of the user without compromising the seams, but may also allow the seam to be separated by a user when it is desired to remove the face mask, for instance, when it is not desired to re-don the face mask after removal.

Regardless, the face mask 100 may then undergo bonding 226 and cutting 228 (e.g. cutting generally perpendicular to the machine direction), to separate the individual face masks 100 from the laminate.

While the invention has been described in detail with respect to the specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention should be assessed as that of the appended claims and any equivalents thereto. 

What is claimed:
 1. A barrier face mask comprising: a mask body formed from one or more nonwoven web layers comprising a seamless filter portion, an upper elastic portion, and a lower elastic portion; at least one elastic strap, wherein each elastic strap is attached to a first side and an opposed second side of the mask body.
 2. The face mask according to claim 1, wherein the mask body further comprises at least two layers, and wherein one or more of the layers is formed from a meltblown nonwoven web.
 3. The face mask according to claim 1, wherein the meltblown nonwoven web has been electrostatically treated.
 4. The face mask according to claim 1, wherein the face mask filters 70% or more of particles having a size of 0.65 microns or greater.
 5. The face mask according to claim 1, wherein the mask body includes a spunbond nonwoven layer and a meltblown nonwoven layer.
 6. The face mask according to claim 1, wherein the mask body includes a spunbond-meltblown-spunbond layer, and a meltblown nonwoven layer.
 7. The face mask according to claim 1, wherein the upper elastic portion, the lower elastic portion, or both the upper elastic portion and the lower elastic portion are disposed between a first and a second nonwoven layer of the mask body.
 8. The face mask according to claim 1, wherein the upper elastic portion, the lower elastic portion, or both the upper elastic portion and the lower elastic portion are laminated to the one or more nonwoven web layers.
 9. The face mask according to claim 1, wherein the at least one elastic strap is formed from the same elastic as the upper elastic portion, the lower elastic portion, or both the upper elastic portion and the lower elastic portion.
 10. The face mask according to claim 1, wherein the face mask comprises at least two straps.
 11. The face mask according to claim 1, wherein the mask body has a length in an extended state of about 200 millimeters to about 350 millimeters.
 12. The face mask according to claim 1, wherein the at least one elastic strap has a length in an extended state of about 200 millimeters to about 350 millimeters.
 13. The face mask according to claim 1, wherein the at least one elastic strap has a width in an extended state of about 25 millimeters to about 75 millimeters.
 14. The face mask according to claim 1, wherein the face mask exhibits an air permeability according to ASTM D737 of about 20 cfm or greater.
 15. A method of forming a face mask comprising: forming a laminate comprising unwinding a first nonwoven web, placing one or more elastic members in an upper region, a lower region, or both an upper region and a lower region, unwinding a second nonwoven web, and laminating the first nonwoven web, one or more elastic members, and the second nonwoven web; attaching one or more straps to the laminate, wherein each strap is attached to a leading edge and an opposed trailing edge of the laminate; wherein the one or more straps are attached to the laminate during an in-line process.
 16. The method of claim 15, wherein the one or more straps are cut off of the laminate prior to attaching the straps to the laminate.
 17. The method of one of claim 15, wherein the second nonwoven web is a meltblown nonwoven web, and wherein the method includes unwinding an untreated meltblown web and subjecting the untreated meltblown web to an electrostatic treatment prior to laminating the meltblown web to the first nonwoven web and the one or more elastic members.
 18. The method of claim 15, wherein the first nonwoven web is a spunbond nonwoven web or a spunbond-meltblown-spunbond fabric.
 19. The method of claim 15, wherein an adhesive is applied to the one or more elastic members.
 20. The method of claim 15, where the laminate, the one or more straps, or both the laminate and the one or more straps are held in a stretched state during lamination, attachment of the one or more straps, or both lamination and attachment of the one or more straps. 